Tire recomendations for Afton Alps

I plan on doing the 24 hour race at Afton in the end of August. Haven't ridden there in over a year, but if memory serves me correct it's mostly hardpack? Probably looking for something with low rolling resistance in a 29er size.

I haven't ridden Afton (grew up 10 miles from there) but for a 29er on dry hardpack I don't think you can go wrong with a Maxxis Cross+Mark on back. Rolls as fast as a semislick, but offers more grip. Haven't tried the C+M in the front so I can't speak to its cornering grip, but rolling resistance doesn't matter quite as much in front anyway. If it were me I'd go with something more all-around like an Ignitor, Bonty ACX or Michelin AT in front.

"People like GloyBoy are deaf. They are partisan, intellectually lazy & usually very angry." -Jaybo

My view - unless you are an elite level racer - tires will not win you a 24 hour race - but they can make your race worse if you pick the wrong tire. You can wind up with too many flats because you chose a too small or light a tire thinking it is faster. On the other hand, pick a slow, fat tire and they can contribute to excess workload and wear you down. That leaves a whole bunch of 'do it all' tires in the middle. Not the lightest, not the fastest, not the biggest - but solid, predictable, quick and tough enough to handle some ill-conceived lines in the middle of the night when you're tired.
I have a couple 29ers and ride out at Afton. I've run 2.2 RRs front and rear and recently added my new favorite front tire - WTB ExiWolf. I find it more secure feeling in the sandy corners. The RR is good - but has soft sidewalls and can be flat-prone for me much below 28psi. RRs and SB8s lack some of the high speed braking capacity that I like. I do NOT like to skid my rear tire at all and on dry hardpack with sand, those 2 tend to want to skid on me a bit. Nevegal rear has tougher sidewalls for the longer format race if you want to avoid flats on the hard summer terrain.
I've also run Bontrager Jones AC-X and like those tires on front and rear on my rigid Salsa Mamasita. They are predictable and hook up very well. They're fairly quick too. The 2.2s come in at about 630 grams and work well on hardpack. Panaracer Rampages are supple, tough and offer great traction - but boy are they slow, slow, slow.

So - for me - Exiwolf up front, then RR as a 2nd choice.
Rear - Jones ACX, then Nevegal (if I want a more comfy, durable, sure footed, set-it-and-forget-it, albeit a tad slower, flat-free ride) then RR - in that order.

When in doubt - ride what you have and feel confident After all, rubber is expensive and it's a recession.